Mobility assisting devices such as canes, crutches, and walkers are used by many people on both temporary and permanent bases. Generally, such devices have tubular lower leg portions, having a rubber foot, or the like, disposed at the distal end. While these devices may be readily used during fair weather conditions, use of such devices is particularly difficult during inclement weather conditions. This is particularly true in snowy and icy conditions as the leg or legs may not maintain a firm footing.
Various modifications have been proposed to enhance the grip of such devices on slippery surfaces, with varying degrees of success. Examples of such proposals are disclosed in the following patents: U.S. Pat. No. 3,949,773 to Marescalco; U.S. Pat. No. 4,434,808 to Burak; U.S. Pat. No. 4,708,1154 to Edwards; U.S. Pat. No. 4,964,430 to Janis; U.S. Pat. No. 4,977,914 to Smerker; and U.S. Pat. No. 5,056,546 to Sharp. The devices disclosed in the Burak, Smerker, and Sharp patents disclose devices intended to provide retractable gripping arrangements. These devices are relatively complex, however, comprising spring-loaded extension/retraction arrangements which may be relatively expensive to manufacture and assemble. In addition, they are highly susceptible to breakage due to the a high number of moving parts.
The references to Janis, Marescalco, and Edwards each disclose tips having circular tip members with multiple teeth. The Janis and Marescalco references disclose a toothed gripping member constructed similarly to a circular hole saw. This circular arrangement of gripping teeth, however, can result in the bending and possibly breakage of one or more teeth as the user applies a force to the tip during usage, particularly when the force is applied in any direction other than absolutely normal to the ground. The cleat of Marescalco, which is stamped from a flat piece of metal and then the four toothed legs bent to a right angled position, is particularly susceptible to deformation during normal use.
Janis attaches the toothed gripping member to the shaft by a screws extending through the member and the shaft, or by a band which extends around the leg and likewise is tightened by screw arrangement. There is potential for the tip to slip from the leg in the case of the use of a band. In either arrangement, the coupling screw may not be readily tightened or loosened without a separate tool, rendering it difficult to utilize the toothed gripping member. Accordingly, Janis proposes an arrangement wherein two canes, for example, are coupled side by side, one being inverted. One of the canes would have a standard distal tip, while the other would have the toothed gripping member such that the user could utilize the appropriate cane for the environment. This arrangement can be expensive, heavy and cumbersome in that it requires the use of two support devices. Even in arrangements incorporating a single shaft with the different tips disposed at opposite ends, use of the device disposes the opposite, potentially soiled or sharp tip adjacent the user's limbs and/or body.
Marescalco attaches the cleat to the leg by coupling the cleat to the standard rubber elastomeric cup-shaped tip, which is removed from the leg for attachment of the cleat assembly, and then replaced on the leg. This may be reversed for removal of the cleat assembly. Alternately, a separate cup-shaped elastomeric tip may be placed over the cleat assembly to utilize the support device on a floor or finished surface. Elastomeric tips of this sort, however, are subject to degradation due to use or environmental conditions. The degradation of elastomeric cup-type tips is prevalent when such tips are repeatedly elastically or plastically deformed, as when the tip is removed or reassembled to the leg or the cleat. The elastomeric tip coupling the cleat assembly to the shaft is particularly susceptible to such degradation due to both environmental and use conditions. As a result, the relative positions of the cleat assembly and leg may shift during use, resulting in uncertain footing to the user and ultimate failure of the attachment.
The foot assembly of Edwards likewise will not provide firm footing to the user. The Edwards disk-shaped foot includes a pad having a plurality of somewhat rounded flexible, resilient fingers extending from its lower surface. Contrary to the representations made in Edwards, it is unlikely that resilient and flexible fingers such as this will provide firm footing on wet or icy surfaces. Further, an elastomeric material, such as would be used in the Edwards device, would not likely provide added traction over conventional elastomeric cup-type tips.
DMI DURO-MED Industries, Inc., of Hackensack, N.J., also markets a adapter which may be bracketed to the distal tip of a leg such that it may be unlatched and pivoted between a position below the rubber tip of the leg and a position along the side of the leg. The adapter includes a washer shaped element from which five teeth or prongs depend, similarly to a circular hole saw. The washer with prongs is supported on a bent wire. As with the Janis and Marescalco references, the prongs of the washer-shaped element are susceptible to bending and deformation due to the forces exerted during normal usage, as is the supporting wire. Additionally, the particular geometry of the DMI device prevents the application of force directly along the axis of the leg. Rather, an application of force to the leg results in moments which are applied along the bent wire, enhancing the likelihood of failure of the device due to plastic deformation of the wire, or failure of attachment points of the wire.